On Feb 15, 8:55*pm, Ed Huntress wrote:

"Investigation of Knock limited Compression Ratio of Ethanol Gasoline
Blends"
James P. Szybist, Adam Youngquist, and Robert M. Wagner
Oak Ridge National Laboratory
Wayne Moore, Matt Foster, and Keith Confer
Delphi Corporation

http://info.ornl.gov/sites/publicati...s/Pub21839.pdf

"It was found that at substantially similar engine conditions,
increasing the ethanol content of the fuel results in higher engine
efficiency and higher engine power. These results can be partially
attributed to a charge cooling effect and a higher heating value of a
stoichiometric mixture for ethanol blends (per unit mass of air).
Additional thermodynamic effects on the ratio of specific heats (..)
and a mole multiplier are also explored.

"It was also found that high CR can increase the efficiency of ethanol
fuel blends, and as a result, the fuel economy penalty associated with
the lower energy content of E85 can be reduced by about twenty
percent. Such operation necessitates that the engine be operated in a
de-rated manner for gasoline, which is knock-prone at these high CR,
in order to maintain compatibility. By using early and late intake
valve closing strategies, good efficiency is maintained with gasoline,
but peak power is about 33% lower than with E85."



Ed Huntress

You have left out this statement.

"The higher efficiency of E85 is not sufficient to compensate for its
reduced
energy content relative to RG, thus there is still significantly
higher fuel consumption for E85."


Dan